A metal roof reflects solar energy instead of soaking it up. In a Nashville summer that means a cooler attic, an air conditioner that cycles less, and a roof that will outlast the asphalt one you’re replacing by two or three times.
That’s the short version. Here’s what’s actually available, what separates the systems from each other, what it costs, and who should stay with shingles.
Why Your Asphalt Roof Makes the House Hotter
Dark asphalt absorbs solar energy and holds it. On a 95-degree afternoon the shingle surface can reach 160 degrees or more, and that heat radiates down into the attic all afternoon and keeps radiating after sunset.
In most Middle Tennessee homes the ductwork and air handler are in that attic. Your system is pushing cooled air through a superheated space, losing some of it before it ever reaches a room. That’s why upstairs bedrooms stay warm no matter what the thermostat says.
What Makes a Metal Roof Cool?
Two properties, and it’s worth knowing both because manufacturers usually only advertise the first.
Reflectance is how much solar energy the surface bounces back instead of absorbing. Emittance is how quickly the surface sheds the heat it did absorb. A good cool roof does both, which is why a coated metal panel outperforms bare metal even though bare metal looks shinier.
Modern coatings use cool pigments that reflect infrared while still reading as a dark color to the eye. That matters, because it means you’re no longer forced to choose a white roof to get the thermal benefit. A dark bronze or charcoal metal roof today can reflect substantially more solar energy than a dark asphalt shingle.
Some systems add above-sheathing ventilation, where the panels sit on battens with an air gap underneath. That gap lets heat move out from under the panel instead of conducting down into the deck. Westlake Royal’s own testing on its Unified Steel stone-coated system reported attic temperatures of 89 degrees under the metal system against 147 degrees under standard asphalt shingle in the same conditions. That’s the manufacturer’s test rather than an independent one, so treat the exact figures as directional, but the mechanism is real and the direction is not in dispute.
The Panel Systems You’ll Choose Between
Standing seam
Vertical panels joined by raised seams, with the fasteners concealed underneath. Nothing penetrates the weather surface, which is why these last the longest and leak the least. Expect 40 to 70 years. It’s the most expensive metal option and the one worth buying if you’re staying in the house.
Exposed fastener panels: Max-Rib, R-Panel, 5V
Corrugated or ribbed panels screwed straight through the face into the deck or purlins. Considerably cheaper than standing seam, faster to install, and common on outbuildings, agricultural buildings and budget-conscious residential jobs.
The tradeoff is the fasteners. Every screw has a rubber washer, those washers harden and shrink under UV, and they need checking and re-torquing around year seven and periodically after. Plan on 25 to 40 years, and plan on maintenance you don’t have with standing seam.
Stone-coated steel
Steel panels finished with a bonded stone granule surface, pressed into profiles that read as shake, slate or barrel tile from the ground. You get metal’s lifespan and impact performance with an appearance that suits neighborhoods where a ribbed panel would look wrong. These are usually the systems that come with above-sheathing ventilation built in.
And the Metals Themselves
- Galvalume steel. Aluminum-zinc coated steel, and the default for residential metal roofing. Strong, dent resistant, good corrosion protection, best price of the durable options.
- Aluminum. Won’t rust at all, forms easily, and is the right call near saltwater. Softer than steel, so it dents more readily from hail and foot traffic.
- Zinc and copper. Both will outlive the building and both develop a patina rather than failing. Both are expensive enough that they’re specified for architecture and historic work rather than chosen on value.
Will It Actually Lower Your Power Bill?
Yes, and less dramatically than the marketing suggests, and here’s the honest framing.
A reflective metal roof genuinely reduces the heat load your air conditioning has to overcome, and in a hot-summer climate like ours that shows up on a bill. But a metal roof over a badly ventilated, under-insulated attic will underperform a well-ventilated asphalt roof. The roof surface is one variable in a system.
If cooling cost is the reason you’re considering metal, do the ventilation and insulation assessment at the same time. It costs very little to look, and in some houses it turns out the cheaper fix delivers most of the benefit.
What Does a Metal Roof Cost?
Expect roughly two to three times an asphalt shingle roof on the same house, with exposed fastener panels at the low end of that range and standing seam or stone-coated at the high end.
Two things make the comparison less lopsided than it looks. The first is service life: if a metal roof lasts 50 years and asphalt lasts 25, you’re comparing one purchase against two. The second is that metal often goes over an existing roof without a tear-off, which removes disposal cost from the job.
Worth asking your insurance agent about as well. Metal is noncombustible and impact-resistant, and some carriers discount for it.
Who Is Metal Actually Right For?
It’s a straightforward call in both directions.
Metal makes sense if you plan to be in the house long enough to use the lifespan, if you’re tired of replacing a roof every twenty years, if the house has a simple roof geometry that suits panels, or if summer heat upstairs is a problem you actually want solved.
Stay with asphalt if you expect to move within a few years, if the budget is the binding constraint, if your HOA restricts roofing materials, or if the roof is heavily cut up with dormers and valleys, which drives metal labor up faster than it drives asphalt labor up.
There’s no wrong answer here. There’s a wrong answer for your house, and it’s usually obvious once someone has looked at it.
Talk to Someone Who Installs Both
L&L Contractors installs metal and asphalt roofing across Murfreesboro, Nashville, Franklin, Brentwood, Smyrna, Spring Hill and the rest of Middle Tennessee. We’ll look at the roof, tell you honestly which one your house is a candidate for, and price both so you can compare real numbers instead of averages.
Call (615) 577-9103 or book a free roof inspection online.
